Engineering Commons^™

Characterization In 2d Sulfides And Graphene Composites For Sensing Applications, Alberto Delgado

Open Access Theses & Dissertations

In this work, we have evaluated 2D layered material composites for opto-electro-mechanical sensing applications. In particular, we have focused on TMDCs and graphite and studied the effects of chemical liquid exfoliation on the structural characteristics of the 2D layered materials, through particle size, x-ray diffraction, Raman and surface area analysis. An approach was developed to combine the solution-processed dispersion with organic and inorganic matrix materials for forming the composites. From Raman Spectroscopy of the ultra-sonicated samples, the I2D/IG>2 for graphite, and for MoS2 the difference between the A1g and E2g peak was 22.85cm-1, consistent with few layer 2D MoS2. …

Mechanically Activated Combustion Synthesis Of Molybdenum Borosilicides For Ultrahigh-Temperature Structural Applications, Alan Alberto Esparza Hernandez

Open Access Theses & Dissertations

The desire to improve the efficiency of power generation gas-turbines has led to a relentless quest for new, ultrahigh-temperature structural materials to replace the current nickel-based superalloys. These materials have reached the maximum allowable operating temperature determined by the melting temperature of these alloys, which is about 1150 °C. These materials could be replaced by molybdenum silicides and borosilicides based on Mo5SiB 2 (T2) phase due to their high melting point and mechanical properties. A major challenge, however, is to simultaneously achieve high oxidation resistance and acceptable mechanical properties at elevated temperatures. One novel approach to improve these properties is …

Combustion Of Novel Thermite Mixtures For Iodine Generation, Sergio Emanuel Guerrero

Open Access Theses & Dissertations

Halogen-containing reactive materials could be used for mitigating the spread of hazardous, active biological microorganisms aerosolized as a result of explosion. The present work exhibits experimental results on the combustion of mechanically alloyed aluminum-iodine (Al-I2) powder mixed with Fe2O3, CuO, MoO3, Bi2O3, and I2O5. Wet mixing was used to prepare the samples, which were then compacted into pellets and ignited with a CO2 laser. A chamber was designed and built to accommodate for combustion and collection of products, and the available laser ignition setup was modified to enable combustion experiments with rapidly burning gas-generating mixtures. High-speed video recording was used …

Numerical Simulation Of The Overlay Tester, Andrea Gutierrez

Open Access Theses & Dissertations

The Overlay Tester (OT) is a relatively new testing procedure that characterizes the cracking resistance of hot mix asphalt (HMA) by evaluating the number of cycles to failure of an HMA specimen. The lack of repeatability and high variability of the results have been a concern to transportation agencies. A careful experimental review of the OT test protocol reveals the complex stress and strain distributions that should be understood in order to improve the certainty associated with the test.

The objective of this Thesis is to present the numerical modeling of the OT test through finite element analysis (FEA). When …

Manufacturing And Mechanics Of Polymer Matrix Composites, Md Shariful Islam

Open Access Theses & Dissertations

Fiber-reinforced composite materials are widely used in the aerospace and automobile industries. Their strength-to-weight and stiffness-to-weight ratios make them suitable to be used in spacecraft, especially as cryogenic tank materials. One of the focus of this dissertation is to investigate the application of woven carbon and Kevlar® fiber composites as cryogenic tank materials. Tensile, bending and short beam shear tests are performed on rectangular specimens at room temperature and after cryogenic exposure (-196°C). It is found that the mechanical properties of these composite materials do not degrade significantly due to cryogenic exposure. It is observed that the failure mode took …

A Novel Approach To Control Corrosion Behaviour On Bio Materials Using Taguchi Method (Design Of Experiments), Sai Dhiresh Kilari

Open Access Theses & Dissertations

In the present work, the Taguchi method, from the design of experiment (DOE) has been used to optimize the dip testing method to test the corrosion resistance of bio degradable materials such as PLA (Polylactic acid)and PCL (Polycaprolactone). A L9 (9) orthogonal array of Taguchi design was used, which involves nine experiments for three parameters (pH, sample, temperature) with three levels was used. Corrosion resistance in various pH change of HCL solution was evaluated by dip tests at various temperatures. Analysis of variance (ANOVA) is performed on the obtained measured data and S/N (signal to noise) ratios. The lower the …

Commercialization Of Cobalt Promoted Molybdenum Disulfide Hydrodesulfurization Unsupported Catalyst, Juan Hilario Leal

Open Access Theses & Dissertations

Catalysis is a key player in the petroleum refining process. Our focus is primarily on the improvement of a commercial HDS (HydroDeSulfurization) hydrotreating catalyst. The commercial catalyst sold today is cobalt promoted molybdenum supported on γ-alumina. Our aim is to work with Porocel Industries LLC to produce an unsupported, cobalt promoted, molybdenum disulfide catalyst by improving on previous work conducted by Dr. Brenda Torres. The catalysts (B3&B5) developed by Dr. Torres were reported to be highly active on real feedstocks and were produced via hydrothermal process. Oxidic Mo, and H2S were used to make an ammonium tetrathiomolybdate precursor that was …

Development Of The Thermal Wire Embedding Technology For Electronic And Mechanical Applications On Fdm-Printed Parts, Daniel Abraham Marquez

Open Access Theses & Dissertations

Additive Manufacturing (AM) has increased in popularity and attracted much attention from many fields such as automotive, aviation, aerospace, and even the fashion industry. Since the early 2000s, Fused Deposition Modeling (FDM) technologies have been the most popular in the AM world ("Wohlers Talk" Popularity of FDM). These technologies have been mainly used for building parts for prototype and structural type of applications such as a fixture for components or a housing for mechanisms.

With the current state of the FDM technologies, the functionality of the parts that are printed are limited to the applications listed before or simply just …

Design Structure Method As Applied To The Structural Organization Of A 5th Genertation Fighter Jet, Israel Michel Michel

Open Access Theses & Dissertations

In current times, the demand for protection against enemies in a volatile geopolitical climate is an increasingly demanding concern. Many countries invest billions of dollars attempting to protect their borders and in fact strive to become the most powerful and dominant war power in the world. As the dollar amount of each country increases, and while other countries seem to always beat each other, the path for innovations and demand is never ending. The complexity of each project continues to grow as they become very sophisticated in their respective field.

In recent decades, itâ??s been proven that whoever reaches the …

Transportation Network Resilience: Evaluation Of Performance Measures, Jessica L. Miramontes

Open Access Theses & Dissertations

The resilience of an urban transportation network is its ability to adapt, absorb, anticipate, and rapidly recover from a disruptive event causing link closures, node closures, and reduced capacity, while providing an acceptable level of service. Several researchers, have performed studies of Transportation Network Resilience (TNR). However, there has not been a clear definition of how to measure or quantify TNR. The objective of this research is to define, quantify and compare the consistency of different measures of TNR and make recommendations to engineers and decision makers. In this research seven proposed parameters have been defined as candidate measures of …

Towards The Scalability And Hybrid Parallelization Of A Spatially Variant Lattice Algorithm, Henry Roger Moncada Lopez

Open Access Theses & Dissertations

The purpose of this research is to design a faster implementation of the spatially variant algorithm that improves its performance when it is running on a parallel computer system.

The spatially variant algorithm is used to synthesize a spatially variant lattice for a periodic electromagnetic structure. The algorithm has the ability to spatially vary the unit cell orientation and exploit its directional dependencies. The algorithm produces a lattice that is smooth, continuous and free of defects. The lattice spacing remains strikingly uniform when the unit cell orientation, lattice spacing, fill fraction and more are spatially varied. This is important for …

Enhancing Surface Finish Of Fused Deposition Modeling Parts Through Targeted Chemicals And Design Of Experiments, Saurabh Nayyar Nayyar

Open Access Theses & Dissertations

Fused Deposition Modeling (FDM) is one of the most popular rapid prototyping (RP) technologies due to its low operational cost, high fabrication speed, and range of applications served. However, FDM fabricated parts generally have poor surface finish quality which have limited their utilization in end-use applications. To enhance surface quality of FDM materials, several researchers have regulated key process parameters using the FDM material, Acrylonitrile Butadiene Styrene (ABS), with varying results. The main goal of this research is to investigate the effects of a post-fabrication chemical treatment process on the surface roughness for FDM parts of the FDM material ULTEM. …

Analysis Of Nitrogen Speciation And Removal In Direct Potable Reuse In El Paso, Texas, Oluwaseye Michael Owoseni

Open Access Theses & Dissertations

Population growth and increasing demand for potable water is causing a need for additional sources to water portfolios in areas with water scarcity. Direct Potable Reuse (DPR) is gaining recognition in these regions and ensuring appropriate measures for the removal of nitrogen and other contaminants cannot be overemphasized. Two nitrogen species, nitrate and nitrite are known to cause harmful effects on young infants below the age of six months. El Paso Water Utilities conducted a pilot test for DPR to ascertain the viability of DPR as an additional source to the current water portfolio.

Non-chlorinated secondary clarifier effluent from a …

Design And Evaluation Of The Impact Of A Multi-Agent Control System (Framework) Applied To A Social Setting, Perez Antonio Perez

Open Access Theses & Dissertations

The objective of this research is to design and analyze the performance of a new mechanism to improve the advising of students in a nontraditional environment. This nontraditional environment includes: a minority serving, commuter campus with a high percentage of transfer students. Specifically, these demographics are unable to keep a tightly controlled cohort of students flowing through to the completion of the curriculum. Students in these circumstances usually have varied course loads and competing priorities due to family and financial needs or other societal responsibilities. Therefore, there is a need for an individualized approach to advising.

University administrations face challenges …

National Evaluation For Development And Exploration Potential Of Mineral Commodities In Produced Waters, Stephanie Ray

Open Access Theses & Dissertations

The U.S. Geological Survey recently updated a geochemical database consisting of data for approximately 160,000 produced waters samples, primarily from petroleum and geothermal reservoirs. Using major and trace elements from conventional and unconventional well types from the database, this Thesis provides a comprehensive, national evaluation for mineral commodity potential in produced waters. Produced waters contain virtually every naturally occurring element and can range in salinity to several times that of seawater. Despite the typical outlook to view produced waters as a waste, they have potential for natural resource development.

This Thesis provides, for each mineral commodity found in the produced …

Modeling Of Piezoelectric Traveling Wave Rotary Ultrasonic Motors With The Finite Volume Method, Ivan Arturo Renteria Marquez

Open Access Theses & Dissertations

In 1983 Toshiiku Sashida developed a new motor concept called Piezoelectric Traveling Wave Rotary Ultrasonic Motor (PTRUSM). The advantages of these motors include high torque at low speed, absence of a generated magnetic field, and high potential for miniaturization. Unfortunately PTRUSMs have some disadvantages that limit the areas of applications for these types of motors. The disadvantages are a short operating life (about 1000 hours), small output power, and the need of a complex motor controller.

On one hand, these motors have been used in satellites, mobile phones, photocopiers, robotic arms, telescopes, automobiles, and camera autofocusing. On the other hand, …

Intrinsic And Metal-Doped Gallium Oxide Based High-Temperature Oxygen Sensors For Combustion Processes, Ernesto Javier Rubio

Open Access Theses & Dissertations

Currently, there is enormous interest in research, development and optimization of the combustion processes for energy harvesting. Recent statistical and economic analyses estimated that by improving the coal-based firing/combustion processes in the power plants, savings up to ~$450-500 million yearly can be achieved. Advanced sensors and controls capable of withstanding extreme environments such as high temperatures, highly corrosive atmospheres, and high pressures are critical to such efficiency enhancement and cost savings. For instance, optimization of the combustion processes in power generation systems can be achieved by sensing, monitoring and control of oxygen, which is a measure of the completeness of …

Systems Engineering Approach To Solve Drug Violence Problem, Jagadish Thimiri Mallikarjan

Open Access Theses & Dissertations

The War on Drugs has caused cartel related violence to increase, creating a challenge for socio-political stability in Mexico. Currently, the U.S. government focuses on law enforcement measures to interdict drugs in the cartel supply lines.The basics of supply-and-demand and system dynamics approach provided a conceptual framework to understand and capture the features of interdiction in illegal drug markets, and provided important insights to solve the drug violence problem.

Ontology-Driven Integration Of Data For Freight Performance Measures, Eduardo J. Torres

Open Access Theses & Dissertations

Transportation performance measures are defined as quantitative and qualitative indicators that rely on data or information to explain mobility, congestion, safety, environmental and other factors. Though performance measures have been used for freeways and other highways, not many have been specified and applied to the freight transportation system. Recently, freight performance measures have been recommended by Federal Highway Administration to quantify the operating efficiency of the freight transportation system on existing infrastructures. This research seeks to expand this concept and to develop a comprehensive freight performance measurement framework. The expanded framework recommended in this Thesis consists of four criteria: safety, …

Microstructural Investigation Of Vintage Pipeline Steels Highly Susceptible To Stress Corrosion Cracking, Monica Adriana Torres

Open Access Theses & Dissertations

The use of pipelines for the transmission of gas offers not only efficiency, but a number of economic advantages. Nevertheless, pipelines are subject to aggressive operating conditions and environments which can lead to in-service degradation [1] and thus to failures. These failures can have catastrophic consequences, such as environmental damage and loss of life [2]. One of the most dangerous threats to pipeline integrity is stress corrosion cracking (SCC). Despite the substantial progress that has been achieved in the field, due to the complex nature of this phenomenon there is still not a complete understanding of this form of external …

Design Of A Thermal Management System For An Oxy-Methane Direct Power Extraction Combustor, Jad Gerges Aboud

Open Access Theses & Dissertations

The overarching goal of this Thesis is to present the design of a thermal management system for an oxy-methane direct power extraction combustor. The design is initiated by performing a 2D analysis on the combustor geometry and then using these results in a 3D model. This is done by using results for heat transfer coefficient and temperatures found from the 2D simulation and importing these to the 3D model. The approach used here couples the combustion process, heat transfer through the chamber wall, and fluid flow behaviors in order to observe the thermal characteristics of the combustor during operation. This …

G-Code Generation For Multi-Process 3d Printing, Callum Peter Bailey

Open Access Theses & Dissertations

Since the inception of stereolithography in the 1980s, interest in 3D printing has exploded, with desktop 3D printers now commercially accessible to the general public. In recent years, next-generation multifunctional technologies have been developed, which combine 3D printing with other technologies such as wire embedding, foil embedding, CNC machining, and robotic component placement, enabling complex parts to be made on a single multifunctional machine.

However, the complexity of these integrated processes exceeds the capabilities of established design tools. To this end, this Thesis aims to develop a multi-functional design solution that can automatically generate final control code for next-generation multifunctional …

A Discretionary Lane Changing Decision Model Based On Fuzzy Inference System, Esmaeil Balal

Open Access Theses & Dissertations

A lane changing event involves up to five vehicles: the subject vehicle, preceding and following vehicles in the original lane, and the preceding and following vehicles in the target lane. Understanding the behavior of the subject vehicle with respect to the surrounding vehicles is fundamental to the study of the safety of a lane change maneuver and for the modeling of lane changing behavior. First, the statistical properties of 10 lane changing parameters were defined and studied using the Next Generation SIMulation (NGSIM) vehicle trajectory data collected at the I-80 Freeway in Emeryville, California, and then tested with data collected …

Case Studies In Implementing Intelligent Compaction In Construction Of Earthwork, Jorge Alberto Beltran

Open Access Theses & Dissertations

The nuclear density gauge (NDG) is the current tool for field compaction quality control (QC) and quality assurance (QA) for soil and base layers in the state of Texas. The Texas Department of Transportation (TxDOT) uses this nondestructive testing (NDT) device to determine the compacted density and moisture content of earthwork and unbound aggregates. However, to provide the missing link between design and quality management parameters, an alternative stiffness-based approach would be more desirable. Intelligent Compaction (IC) is defined as continuous assessment of mechanistic soil properties (stiffness, modulus) through roller parameters (frequency, amplitude and speed) integrated with global positioning system …

Influence Of The Stress Path, Moisture, And Fine Content On Permanent Deformation Of Geomaterials, Uriel Brian Arteaga

Open Access Theses & Dissertations

Permanent deformation within the unbound granular is a predominant feature that results in the degradation and loss of serviceability to the pavement structure as the passage of traffic wheel loads accumulate. Proper characterization of the multi-layer structures is necessary to improve the rutting performance by mechanistically identifying the factors that contribute to the progression of plastic deformations. A consequence of ignoring these features results in the underestimation of the rutting potential, which amounts to premature failure. Current rutting models fail to incorporate factors such as moisture state, gradation, and stress-paths which are paramount to proper characterization of base and sub-base …

Design Of Experiments-Based Scara Robot Parameter Evaluation For Embedding Electronics Into 3d Print, Sreekara Charith Boppana

Open Access Theses & Dissertations

Additive manufacturing processes combined with enhanced technologies for electronics production enables a highly flexible manufacturing of personalized 3D electronic devices. Due to the enormous progress within the last years, these technologies made their way from prototyping towards manufacturing. The growing request for products manufactured in batch size, making use of a robot to incorporate the electronic components necessary to make functional 3-Dimensional-Structural Electronics will extend the mass production possibilities. There is significant interest in automation of a process is which parameters are influential in the occurrence of assembly defects and which adjustments should be made to those variables to reduce …

Investigation Of Ti-6al-4v Alloy Response To Atmospheric Re-Entry Exposure, Jessica Lynn Buckner

Open Access Theses & Dissertations

Ti-6Al-4V is a widely used aerospace alloy for its high strength-to-weight ratio and high operating temperature properties. Despite widespread use, titanium and its alloys have been shown to ignite in oxygen and nitrogen rich test streams. The reactivity of titanium is attributed to the high solubility for oxygen that increases with temperature, accelerating the oxidation rate and resulting in a combustion reaction. When introduced to the monatomic oxygen rich and high enthalpy re-entry environment, Ti-6Al-4V X-link components from the space shuttle Columbia exhibited accelerated oxidation and combustion behavior. Ti-6Al-4V metal plates tested in the simulated re-entry environment of an arc-jet …

Vascularization In Interconnected 3d Printed Ti-6al-4v Foams With Hydrogel Matrix For Biomedical Bone Replacement Implants, Victor Correa

Open Access Theses & Dissertations

Abstract:

Vascularization or angiogenesis on newly implanted metal orthopedic implants has remained a challenge in the field of tissue engineering. In this research, an interconnected foam structure of Ti-6Al-4V was micro-fabricated by Electron Beam Melting (EBM) technique. The foam in question has a density of 1.77g/cm3 with 60% porosity and a tensile strength of 18GPa. An Extracellular Matrix based hydrogel was added as an aqueous matrix to the foam in question. Hypoxia mimetic stress has been closely related to many wound healing biomedical applications as it increases survival and proliferation molecular signals. To that end, increased expression of Hypoxia-Inducible Factor-1α …

Materials Characterization Of Deposits On Starboard (Inboard) Elevon Actuator Shaft Recovered From Space Shuttle Columbia, Mayra Contreras

Open Access Theses & Dissertations

With the new era of space exploration upon us and the Orion spacecraft currently being tested, which would replace the Space Shuttle as the orbiter that will transport humans into space once again, safety assurance is the main component for a successful mission. Aerospace materials have always played a big role when it comes to safety assurance. Having the knowledge of what materials are suitable to keep using when designing the future spacecraft that will take humans to Mars is fundamental in order to be confident that the vehicle and all that comprises it will function as envisioned. Expanding the …

Magnesium-Based Combustion Synthesis Of Advanced Materials For Energy And Space Applications, Armando Delgado

Open Access Theses & Dissertations

As energy problems become more challenging, interest in low-energy-consuming methods for the fabrication of materials increases. Combustion synThesis is one such method because it is sustained by reaction heat release instead of external energy input. In the present work, combustion synThesis approaches are applied to the production of construction materials from lunar and Martian regolith and to the fabrication of magnesium silicide (Mg2Si), a promising thermoelectric material for high-temperature applications. In both cases, magnesium (Mg) was used as one of the main reactants and similar experimental approaches were employed.

Recently, it has been proposed to use combustion of lunar regolith …